Superior oblique

Musculus obliquus superior

Sensory (eye & ear)Deep musclesHeadLeft and right

View left in 3D View right in 3D

What it is

The longest, thinnest eye muscle. Its belly runs forward along the upper inner orbital wall; its round tendon passes through a cartilage pulley (the trochlea) and turns back and outward under the superior rectus to fan out on the upper-outer back quarter of the globe.

Function

Rotates the top of the eye inward (intorsion) and depresses and abducts it - most effective at looking down when the eye is turned in, as in reading or walking downstairs.

Size

Belly ~40 mm, reflected tendon ~20 mm; the reflected part runs ~54 degrees to the visual axis.

Clinical note

Its nerve, the trochlear (CN IV), is the thinnest and longest intracranial cranial nerve; a palsy gives vertical double vision that patients reduce by tilting the head away from the affected side.